I would like to plant several Ash trees in the border between the sidewalk and street at our home in northwest Seattle, and I would very much appreciate talking with an Ash tree expert on their recommendations. Can you help me?
I can’t claim to be an ash expert, but I may be able to find information for you about some of the trees which do well here. First, though, I need to ask you which tree you are referring to when you use the common name ‘Ash.’ Sometimes this refers to Sorbus (mountain ash), and sometimes to Fraxinus (true ash).
The City of Seattle has information about planting street trees, including lists of approved trees, trees approved with serious reservations, and trees one should not plant. (From my observations, inclusion on the list isn’t always an indication that a tree does well here. I think it is more an indication that the tree meets some criteria, such as not making excessive litter, or drastically buckling pavement.)
I can tell you from first-hand observation that the many specimens of Fraxinus angustifolia (cultivars ‘Raywood’ and ‘Flame’) are beautiful (fall color, graceful shape) but brittle in windstorms. Many were lost along the northern stretches of 35th Avenue NE during a major winter storm several years ago. Their roots may also lift sidewalks. Valerie Easton has written about these trees in her Seattle Times gardening column. Below is an excerpt:
“The beautiful flame ash trees (Fraxinus angustifolia ‘Raywood’), which are the sole reason I drive to work along 35th Avenue Northeast, are wreaking havoc with miles of sidewalk.”
Local tree expert Arthur Lee Jacobson has updated information about trees listed in his book Trees of Seattle which are no longer there:
“Green ASH. Fraxinus pennsylvanica Marsh.
The 2006 mid-December storm blew down one of 7 on 13th Ave E. It was a male. Also two of six specimens at Madrona Park went down then.
Narrowleaf ASH. Fraxinus angustifolia Vahl ‘Dr. Pirone’
The 2006 mid-December storm blew down about half on 27th Ave.”
More from Valerie Easton:
Q: I enjoy the trees on 35th Avenue Northeast in Lake City behind the Fred Meyer store. They are so tall and graceful, and this time of year they look so feathery with gorgeous purple leaves they seem to go from green to purple, skipping any yellow or orange phase. What the heck are they?!
A: The trees lining 35th Northeast are flame or claret ash (Fraxinus angustifolia ‘Raywood’), which turn a stunningly rich shade of bronzey-purple in autumn. If you can tear your eyes away from the foliage, you’ll see that their roots are heaving up the sidewalk, so they are probably not the best street trees despite their beauty.
The variety ‘Raywood’ needs full sun and moderate amounts of water, and it grows quickly to 35 feet tall (or so say the books many of the trees along 35th look much taller than that).
To return to the identity of the ‘Ash’ you asked about, if you are talking about mountain ash (Sorbus), the species vary widely in size, and one of the most common species around here, Sorbus aucuparia, is listed by King County as a “weed of concern.”
There is a grove of Sorbus in the Arboretum where you can study several different species of mountain ash.
I have seen a fairly uncommon species, Sorbus aria ‘Lutescens,’ planted in a parking strip to great effect. Great Plant Picks has more information about it.